This disclosure is directed to a wireline tool catch mechanism. In a completed oil well, periodic servicing of the well is required. This is normally accomplished by installing certain equipment at the well head. The equipment will typically include equipment for enabling the wireline to enter into the well. This is accomplished by usually installing at the well head a blowout preventer. A lubricator is also installed. A wireline is extended through all of the equipment and support some kind of down hole tool. The tool typically has the form and shape of an elongate cylindrical body of specified length.
The present invention is a trap apparatus to be installed in conjunction with the blowout preventer and lubricator to catch and hold the down hole equipment supported on the wireline. As the wireline tool is retrieved, it is important to get it above the trap so that the trap can operate, thereby closing the passage and preventing dropping of the tool. The tool is, therefore, caught above the trap. Above the trap, it is safe against accidental loss.
One prior art device is depicted in U.S. Pat. No. 3,435,895. This apparatus utilizes a single gate which pivots at one side of the passage and rotates into a tool catching position. A single gate is formed in the shape of a bifurcated spade having a deep slot cut through the middle. Moreover, there is a large side pocket on the body to enable the single gate to fold to the side. Manufacturing costs are inevitably increased because this construction is not made from tubular stock and is difficult to machine in contrast with tubular goods.
The present invention is readily contrasted with the referenced patent in that it utilizes a pair of opposing pivotally mounted gates which function opposite one another. They function together to fully close the passage. Moreover, they are formed of cooperating semicircular components. On retraction, they are sufficiently small and shaped such that the entire apparatus can be fabricated from tubular stock and does not require an odd shaped casting.
Another advantage which the present apparatus has is found in an external indicator of its position. The position indicator comprises a side located indicator pin which inevitably forms an indication of whether or not the twin gates are down or up. Through the use of color coding and the like, this is extremely helpful to determine the operative state of the trap device of the present invention. Another important advance found in this apparatus is the utilization of a pair of opposing pivotally mounted gate pieces. They are identical in construction to one another. When both are down, they completely block across the passage. They come close to contacting one another, not closing with a very narrow slot left between them.
The present invention is improved in the aforementioned features over the cited prior art. These features and others will be noted on considering the mode of operation of this equipment. It is primarily an elongate tubular body adapted to be installed above a blowout preventer in conjunction with a lubricator above a producing well. The elongate tubular body terminates in a lower coupling for ease of connection. It incorporates a pair of tubular members threaded together at the central portions which enlarge the body to receive an internally located sleeve which moves upwardly and downwardly. The sleeve is driven by hydraulic power through fluid introduced on the exterior above or below an encircling ring or shoulder. The shoulder is positioned between a pair of hydraulic ports to define upper and lower hydraulic chambers. The sleeve is moved upwardly or downwardly as specified. The sleeve supports a pair of opposed pivot mounts for a pair of gates. They are constructed identically to one another and are deployed on opposite side of the sleeve. The gates have a protruding tab. The tab extends beyond the sleeve. When opposite a cavity, the tabs are provided with room to enable them to pivot to a horizontal posture, thereby enabling the two gates to be positioned on a common plane transverse to the axial passage for closing the passage. They rotate downwardly into the horizontal position and rest on a transverse shoulder. In this position, they are able to support a wireline tool on the top face. The two gates cooperate to support the tool. By contrast, they pivot up and retract to a position against the side wall of the surrounding sleeve or tubular body. In the retracted position, the axial passage is cleared to enable the wireline line supported tube to drop past the gates.
The equipment further includes means forming an external indication of the position of the gates. When they are in the retracted position, the tool is open to free axial movement of the wireline tool. The indicator includes a spring loaded indicator rod which extends to the side and which can be observed to determine the position of the sleeve. This, in turn, indicates the operative state of the gates.